A wide variety of angioplasty devices exist for dilating the lumen of a body vessel, such as a vein or artery. Many of these angioplasty devices use expandable balloon catheters which are positioned inside the blood vessel at the point where the lumen is to be dilated, such as at an area of the lumen which has been constricted by arteriosclerotic plaque. In accordance with accepted procedures, once the catheter has been properly positioned within the blood vessel, the expandable balloon catheter is inflated with fluid. As the balloon expands, it dilates the lumen of the blood vessel to compress the obstructive tissue and open the constriction. After the constriction or stenosis has been opened, the balloon is deflated and removed to permit the restoration of blood flow in the vein or artery.
One means by which a balloon catheter may be positioned inside the blood vessel is to attach it to a guide wire, and then insert the combined catheter and guide wire into the vessel. In the case of other angioplasty balloon catheters, however, a guide tube or wire is prepositioned in the artery before the balloon catheter is inserted. Of course, one disadvantage with such a balloon catheter is that it requires two insertion procedures. On the other hand, when the guide wire is integrated with the balloon catheter, only one insertion procedure is required. Regardless which system is employed, a guide wire or some other stable platform with a low profile is required to properly position the relatively flexible and easily bent balloon.
To be effective, an integrated guide wire/balloon catheter must have certain characteristics. For instance, it must be functional for both positioning the catheter inside the body and for communicating fluid to and from the balloon. To do this, the guide wire should be hollow, yet have a small enough outside diameter to fit within and through a blood vessel. Further, and somewhat at odds with its requirement for a small outer diameter, the guide wire/balloon catheter should also have a large enough inside diameter for its lumen to permit adequate fluid communication through the catheter to the balloon. As can be readily appreciated, a relatively large lumen for the catheter is desirable to provide for relatively rapid inflation and deflation of the balloon. This capability is needed to minimize the time during which blood flow through the vessel is substantially impeded by an inflated balloon. Increasing the catheter's lumen while maintaining a necessarily small outer diameter, however, decreases its wall thickness and hence its structural strength. As can readily be appreciated, a structurally weak hollow guide wire may kink or deform, or may provide insufficient catheter steerablity and pushability during the insertion procedure. Stated differently, a guide wire should preferably be strong enough to withstand a relatively large amount of bending during the insertion process without buckling or undergoing plastic deformation. Further, the patency of the lumen is essential to allow for rapid deflation of the balloon and removal of the catheter if the patient should become distressed.
In addition to the above considerations, a balloon catheter mounted on the end of a positioning guide wire may become distorted and twisted when torque is applied to it as the guide wire is being inserted and steered into a curved blood vessel. Catheter twist is undesirable because it tends to collapse the lumen of the catheter and thus inhibit rapid and complete balloon expansion when fluid is infused into the balloon. Additionally, catheter twist is undesirable because it impedes effective transmission of torque from the guide wire's proximal end to the steerage distal end, which is effectively being steered.
In light of the above discussion, the present invention provides for a guide wire with integral angioplasty balloon which allows for relatively rapid inflation and deflation of the angioplasty balloon. Further, the present invention provides for a guide wire with integral angioplasty balloon which may be easily and effectively inserted into a human blood vessel in a single insertion procedure. Still further, the present invention provides for a guide wire with integral angioplasty balloon which is steerable into the lumen of a body vessel but which will not unduly distort or kink during insertion. The present invention provides for a guide wire with integral angioplasty balloon which may be easily and effectively positioned at a desired location within the blood vessel. Additionally, the present invention provides for a guide wire with integral angioplasty balloon which, together as a single unit, substantially prevents balloon through the catheter's guide wire. Finally, the present catheter windup when torque is applied to the catheter invention provides for a guide wire with integral angioplasty balloon which is relatively easy to manufacture and comparatively cost-effective.